High-Efficiency Advanced Vehicles

No matter what the fuel, the higher the fuel economy of a car or truck, the less it pollutes.

Fuel economy becomes even more important when you consider the growing popularity of sport utility vehicles (SUVs). According to Automotive News, General Motors expects SUVs to outsell every other car and truck by 2005. If we could double the fuel economy of SUVs, we could save more than 5000 gallons of fuel per vehicle over its lifetime.

Some new cars on the market now offer really impressive improvements in fuel economy. Other advanced technologies are under development and will soon be available in new vehicles.

Electric Vehicles

In 2000, two — Honda and Toyota — began selling hybrid electric vehicles (HEV). Additional models from other automakers are expected to follow.

HEVs, which combine the internal combustion engine of a conventional vehicle with an electric motor, can achieve about twice the fuel economy of conventional vehicles. An energy system stores the power to run the electric motor. Batteries are by far the most common energy storage choice. But researchers are still exploring other energy storage options.

HEVs reduce smog-forming pollutants by running more efficiently. But because of their internal combustion engines, they are not zero-emission vehicles. However, the first HEVs on the market emit a third to one half the amount of greenhouse gases emitted by standard gasoline vehicles. Later models may cut emissions even more.

Advanced Drive Trains

The drive train is the system within the vehicle that transmits power from the engine and directs it toward the wheels, and varies the amount of force (torque) that rotates the wheels.

Compression-Ignition Direct-Injection (CIDI) Engines

CIDI engines are the most efficient inter- nal combustion engines available today. Vehicles with CIDI engines have the ability to directly inject fuel into the combustion chamber of an engine to ignite the fuel by compressing it.

Turbocharged Direct-Injection (TDI) Diesel Engines

This is the turbocharged version of the CIDI engine, which is popular in Europe and now available in automobiles sold in the United States. The TDI engine's fuel economy is 20 percent greater than conventional diesel engines.

Spark-Ignition Direct-Injection (SIDI) Engines

Standard gasoline engines use a spark to ignite the fuel. Like CIDI engines, SIDI engines inject fuel directly into the combustion chamber. However, SIDI engines have the advantage of burning gasoline and different types of alternative fuels.

Fuel Cell Vehicle

The fuel cell is one of the hottest advanced vehicle technologies. Many researchers expect this technology to be used in vehicles by 2010.

Fuel cells, which convert hydrogen and oxygen into electricity, have been researched for use in vehicles for many years, and their development and performance have progressed. Because they produce only vapor as emissions, fuel cells are ideal power sources for transportation. They can be used as the main power for an electric vehicle, or in conjunction with an internal combustion engine in a hybrid vehicle.

Fuel cells convert the chemical energy of a fuel into usable electricity and heat without combustion as an intermediate step. Fuel cells are similar to batteries in that they produce a direct current by means of an electrochemical process. Unlike batteries, however, they store their reactants (hydrogen and oxygen) externally and operate continuously as long as they are supplied with these reactants.

Today, researchers are working on making fuel cell components—considering their size, weight, and cost— competitive with internal combustion engines. Although researchers still have several obstacles to overcome, fuel-cell technology has the potential to provide us with another energy-efficient, cost-competitive transportation option that will help lower emissions and reduce dependance on petroleum.